As the use of high strength steels increases in automotive applications, there is a growing demand for steels of increased strength without sacrificing formability. Growing demands for weight saving and safety requirement motivate intensive elaborations of new concepts of automotive steels that can achieve higher ductility simultaneously with higher strength in comparison with the existing Advanced High Strength Steels (AHSS). The first group (“generation”) of AHSS includes low alloyed DP (Dual Phase), TRIP (Transformation Induced Plasticity), CP (Complex Phase) and martensitic steels. Steels with TRIP effect demonstrate advantageous balance of strength and ductility, but commercial TRIP grades are limited mostly by tensile strength of 800 MPa. The “second generation” of AHSS is represented by highly alloyed (up to ˜17-22 wt. % Mn) and extremely ductile TWIP (TWinning Induced Plasticity) steels having up to 50% elongation at 1000 MPa tensile strength, although they have not found commercial application yet.
Thus, there is a need in the art for 3rd generation AHSS, which are less alloyed than TWIP steels and have intermediate properties, such as a combination of 1000-1200 MPa strength and 20-30% elongation.